How do you solve the system x + y = 12 and y = 2x?

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Answer 1 · 2018-07-27T09:54:05

$x=4, \ \ y=8$

Given equations:

$x+y=12\ .....(1)$

$y=2x$

$2x-y=0\ .........(2)$

Adding (1) & (2), we get

$x+y+2x-y=12+0$

$3x=12$

$x=12/3$

$x=4$

setting $x=4$ in (1), we get

$4+y=12$

$y=8$

hence the solution is

$x=4, \ \ y=8$

Answer 2 · 2018-07-28T00:55:08

$(4,8)$

We already have $y$ defined in terms of $x$ , so we can plug this value into the first equation to get

$x+2x=12$

Combining like terms, this simplifies to

$3x=12$

Dividing both sides by $3$ m we get

$x=4$

We can plug this value into the second equation to get

$y=2(4)=>y=8$

Therefore, the solution of these two equations is at the point

$(4,8)$

Hope this helps!